Self-tuning amplifier

Details Self-tuning amplifier Self-tuning amplifier

1999-11-05

2001-07-31

Pascal, Robert (Department: 2817)

Amplifiers

With semiconductor amplifying device

Including frequency-responsive means in the signal...

C330S296000

Reexamination Certificate

active

06268774

ABSTRACT:

FIELD
This invention relates to amplifiers, and more particularly to self-tuning amplifiers.
BACKGROUND
A low noise amplifier is often used to initially amplify low level signals, such as radio frequency signals used in communication systems. Desirable properties in a low noise amplifier include a low noise figure and a high gain.
FIG. 1
is a schematic diagram of one embodiment of prior art low noise amplifier
100
. Low noise amplifier
100
includes transistors
103
and
106
, inductors
109
and
112
, and impedance matching network
115
. Signal source
118
is coupled to impedance matching network
115
. The output signal from impedance matching network
115
is coupled to transistor
103
. Transistor
103
is connected in series with transistor
106
and inductors
109
and
112
. Inductor
109
functions as a direct current bias conduit and radio frequency load while assisting in tuning out the input capacitance of the following stage. Inductor
112
is capable of tuning the input impedance of transistor
103
to match the signal source impedance while degenerating the source to improve the linearity of the amplifier.
Tuning affects the noise figure, gain, and stability of a low noise amplifier, so tuning is an important feature of the input stage of a low noise amplifier. Inductor
112
alone is not sufficient to provide precise tuning for low noise amplifier
100
, since the value of the parasitics that inductor
112
is attempting to tune are typically not known and are difficult to characterize experimentally. A value for inductor
112
is chosen to provide “coarse” tuning of the input impedance. Impedance matching network
115
is added to provide “fine” tuning. Unfortunately, impedance matching network
115
requires the use of expensive off-chip components. Since the inductor values capable of being realized in complementary metal-oxide semiconductor (CMOS) process are poorly controlled and restricted to a very narrow range, the use of off-chip components is common in the fabrication of low noise amplifiers using CMOS processes. Therefore, inductor
112
cannot be used alone to precisely tune low noise amplifier
100
to the source impedance.
For these an other reasons there is a need for the present invention.
SUMMARY
An apparatus includes an amplifier and a voltage source. The amplifier has an input impedence and a substrate body. The voltage source is coupled to the substrate body and is operable for controlling the input impedence.


REFERENCES:
patent: 4179668 (1979-12-01), Schuermann
patent: 4504908 (1985-03-01), Riederer et al.
patent: 4783849 (1988-11-01), Muterspaugh
patent: 4921465 (1990-05-01), Hietala et al.
patent: 5122915 (1992-06-01), Klein et al.
patent: 5274339 (1993-12-01), Wideman et al.
patent: 5493715 (1996-02-01), Humphreys et al.
patent: 5564098 (1996-10-01), Rodal et al.
patent: 5574993 (1996-11-01), Kobayashi et al.
patent: 5600187 (1997-02-01), El-Hamamsy et al.
patent: 5729171 (1998-03-01), Straw et al.
patent: 5764101 (1998-06-01), Archer
patent: 5825206 (1998-10-01), Krishnamurthy et al.
patent: 5838388 (1998-11-01), Blanc
patent: 5847581 (1998-12-01), Allen
patent: 5929707 (1999-07-01), Samuels
patent: 5939940 (1999-08-01), Patti
patent: 5939942 (1999-08-01), Greason et al.
patent: 5999043 (1998-10-01), Zhang et al.
patent: 6140877 (2000-10-01), Forbes

Affiliated with

Also associated with

Rating

Self-tuning amplifier does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Self-tuning amplifier, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Self-tuning amplifier will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2454491